安全修复和管理员账号密码自定义

.env.example

@@ -10,6 +10,9 @@ DATABASE_URL=sqlite+aiosqlite:///./qquiz.db
 # JWT Secret (must be at least 32 characters; generate randomly for production)
 SECRET_KEY=
 
+# Default admin username (must be at least 3 characters; default: admin)
+ADMIN_USERNAME=admin
+
 # Default admin password (must be at least 12 characters; generate randomly for production)
 ADMIN_PASSWORD=